1. Technical Field of the Invention
The present invention relates to electrodes of various batteries and an assembling method thereof.
2. Description of Related Art
FIGS. 8A and 8B show an electrode plate group 31 to be accommodated together with electrolyte within a battery case to constitute a prismatic battery. The electrode plate group 31 is composed of a large number of positive electrode plates 32 and negative electrode plates 33 that are alternately stacked upon one another with intervening separators 34 therebetween. As shown in FIG. 8B, the electrode plates 32, 33 are laterally offset from each other so that side edges on one side of the positive electrode plates 32 and those of the negative electrode plates 33 are protruded outwards in opposite directions, and these protruded side edges of the electrode plates constitute respective leads 32a, 33a. A positive collector plate 35 and a negative collector plate 36 are abutted perpendicularly on the leads 32a, 33a of the positive and negative electrode plates 32, 33, respectively, and joined thereto by welding.
The electrode plate group 31 is formed such that negative electrode plates are arranged on both outermost sides thereof. After welding the collector plates to the side edges of the electrode plate group by electronic beam welding or the like, resistance across both collector plates is measured for inspection for short circuits, and the electrode plate groups that have passed the short-circuit test are inserted into battery cases.
FIG. 9 shows a prior art positive or negative electrode plate 32 or 33. The electrode plate is rectangular, and substantially the entire surface thereof is coated or filled with mixture 37 except the lead 32a or 33a disposed on one side edge thereof. The electrode plate further has positioning holes 38 used when stacking the electrodes, spanning into the area coated with the mixture 37.
The mixture that has been applied on core metal sheets of the electrode plates is apt to fall off particularly when punching the electrode plates to form such positioning holes 38. Also, during transportation and assembling of electrode plates, the mixture can be readily peeled off by surrounding equipment or tools contacting thereto particularly at the three side edges other than the side edge where the lead 32a or 33a is formed. The falling mixture may adhere to the surface of electrode plates and cause short-circuiting later.
Such problem would not arise as long as the electrode plates are manually handled using jigs with sufficient caution. Manual assembly would be, however, unpractical in view of its extremely poor working efficiency. Thus there was the need for solving the problem of falling mixture that may lead to short-circuiting in the process step of assembling electrode plates into a battery.
The present invention has been devised in light of the above-described problem in prior art, and it is an object of the invention to provide electrodes and an assembling method thereof, by which mixture paste coated on electrode plates is prevented from falling off during the assembling process of electrode plates, so that resultant electrodes will be free of short circuits.
A rectangular electrode for a battery according to the invention includes a mixture coated part having a core material and a mixture coated thereon and occupying substantially an entire surface of the electrode, a lead part on one side edge of the electrode where no mixture is coated, and a positioning hole formed only in the lead part.
A reinforcing member may be joined to the lead part at least around the positioning hole for increasing rigidity thereof.
According to another aspect of the invention, a rectangular electrode for a battery includes a mixture coated part having a core material and a mixture coated thereon, a lead part on one side edge of the electrode where no mixture is coated, and a mixture non-coated part on one side edge of the electrode opposite from the lead part.
An additional mixture non-coated part may be provided on both side edges orthogonal to the lead part.
Further, the lead part may include a guiding notch for fixedly positioning the electrode in a lengthwise direction thereof.
A method for assembling electrodes according to the invention includes the steps of:
holding a plurality of electrodes of a first polarity in stacked arrangement within a first magazine;
holding a plurality of electrodes of a second polarity opposite the first polarity in stacked arrangement within a second magazine;
arranging a plurality of first magazines and second magazines in alternate arrangement along a transfer path of a moving assembling jig having a positioning pin thereon;
feeding the assembling jig intermittently along the transfer path, stopping at a position opposite either one of the first magazine and the second magazine; and
transferring the electrodes of the first polarity one by one from the first magazine onto the assembling jig at a halt, positioning of the electrodes with respect to the assembling jig being achieved by the positioning pin; and
transferring the electrodes of the second polarity one by one from the second magazine onto the assembling jig at a halt, such that the electrodes of opposite polarity are stacked alternately on the assembling jig.
The first or second magazine includes a guide rail extending on an inner surface thereof in a stacking direction for engagement with a corresponding guiding part provided in the electrodes, and a storage space therein which, in a state that the electrodes are accommodated within the first or second magazine with their guiding parts engaging with the guide rail, permits a clearance to be formed between three side edges of the electrodes and the inner surface of the first or second magazine.
While novel features of the invention are set forth in the preceding, the invention, both as to organization and content, can be further understood and appreciated, along with other objects and features thereof, from the following detailed description and examples when taken in conjunction with the attached drawings.